Train-control system



1929- c. s. BUSHNELL 1,735,737

TRAIN CONTROL SYSTEM Filed March 31, 1927 l qw'zza,

Patented 19, 153579 rarest GEIAHLES S. BUSHNELL, 01E ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILNVAY SIGNAL COMPANY, OF NEW YORK TRAIN-CONTRGL SYSTEM Application filed March 31, 1927.

.is present invention relates in general train control systems, and has more speercnce to an intermittent inductive ting current type of system employing neumatic engine circuit including acn. owledging and reset means.

It usual in the systems of the character above referred to, which employ electrical engine circuits, to provide car-carried apatus controlled in accordance with the lac conditions ahead, and in turn controling a train control device whereby the moveoi the train is aiiected, under certain '3 nt conditions, in an automatic manner, unless an acirnowledging act be performed. In the event a restricting is incurred, to restore the parts to normal, it is necessary to operate a reset device. It is usual to employ tuned cir cuits which become detuned at particular times, as when the reset device must be operated, due to which detuning the operating currents are so reduced as to leave but a slight margin of current on the side of safety. lVith the above and other considerations in mind, it is proposed, in accordance with invention, to provioe an electro-pneuc the engine circuit being pneuma 1c in c racter, to thereby obviate the above pointed out detect of the slight margin of operating current on the side of safety.

lriore specifically, a pneumatic engine circuit is provided, having a properly safeguard acknowledging and reset means, which need only be positioned at some point in the engine kept at a sufficiently high temperature to p vent danger of freezing up of the va air lines employed.

.er objects, purposes, and character- 'ures of the invention will appear as ption progresses, reference being accompanying drawing, showing, Y w of illustration, and in a quite manner, one form of appliron as applied to a simplified intype of train control system.

e figure or drawing is a schematic rese. tation or" the present invention apto a train control system.

" I o the drawing, a trackway is trails It, separated into Serial No. 179,321.

blocks by usual insulating oints 2, each block having a signal 3, shown in the present instance as of the semaphore type, and an inductor 1, comprising cores 4-, positioned adjacent its entrance end. The various control devices and circuits for the signals and the inductors are not shown or described, since they may be of any usual or desired form, and are net in any manner essential to a complete understanding of the present invention. iiLS represented by dotted lines connecting the signals with the adjacent inductors, each inductor so controlled in accordance with the trzziiic conditions ahead, as to be active under caution and danger conditions, and inactive under clear conditions, as will be readily understood by those versed in this art. This control can, for example, be of the general tyre shown in the patent to W. K. Howe, 1,604,098, Oct. 19, 1926.

Carried on the car, represented diagrammatically by wheels and axles 5, is a receiver R comprising a core 6 having primary and secondary windings P and S thereon, the primary windings being included in a circuit in series with a tuning condenser 7 and a source of alternating current 8, of a preferably higher than commercial frequency, as 360 cycles per second. The secondary windings S are included in a tuned circuit including a condenser 9, and coils 10 of a main relay MR having a core 11 and a pivoted armature l2, biased to retracted position by a spring 13. The condensers 7 and 9 tune their respective circuits for the frequency of alternating current employed.

The apparatus thus far described, operates in a following manner. Upon a car 5 passing an inductor I, the car-carried receiver R has its core 6 positioned over the trackway inductor in inductive relation thereto, whereby, it the inductor be inactive, corresponding to clear conditions, the receiver is not affected, but it the inductor be active, corresponding to either caution or danger conditions, he receiver is so affected as to change the distribution of magnetic flux produced by the primary windings P, and passing through the secondary windings S, as to reduce, to zero, or substantially to zero, the induced.

current normally flowing through such sec ondary windin and the coils 10 of the main relay ME, to thereby de-energize the relay and cause the releasing of its armature 12. The particular manner in which the inductor and receiver co-act need not here be described in detail, it being borne in mind that the primary magnetic flux passing through the sec ondary coils S, when affected by an active inductor, is at least sutliciently reduced to decnergize relay MR.

The pneumatic engine circuit of the invention. includes a primary valve PV, and a secondary valve SV. The primary valve housing is divided into two chambers by a ported partition 1d, and has a control valve rod 15, hearing, at its upper end, against armatnre 12 of relay MR, so as to be opened or closed in accordance with the position of the armature in retracted or attracted position respectively, the upper chamber of the primary valve having a vent 16 to atmosphere, and the lower chamber being connected through a pipe 17, to a reset sylphon, Res S which is merely a chamber having collapsible walls, similar to an accordion. which chamber expands lengthwise under pressure and collapses or contacts when relieved of pressure.

The secondary valve SV comprises a housing divided by partitions into an upper, a middle and a lower chamber, the upper one of which is connected to atmosphere through a port 18, the middle one of which is connected to a pipe 19, and the lower one of which is connected to a pipe 20, through a constricted opening 21. W i thin the housing is a valve stem 22, carrying two oppositely facing valve members 23 and 24., for respectively controlling the ports in the upper and lower partitions forming the three chambers referred to. The valve stem 22 is urged in an upward direction, by a spring 25, while it is held in its lower position, by means of the sylphon Res S, when the latter is supplied with pressure fluid from the large actuator cylinder through pipes 32, 36 and 35, asis normally the case.

Three manually operable valves, a double heading, a reset, and an acknowledging valve, DH, lies V and A070 V, are provided the first and last each including a casing vrithin WfilCll is a rotary valve plug having diametrical port and a right angle port connecting therewith while the valve Res V has a rotary valve plug with a diametrical port and a connecting port at substantially (30 thereto. Each valve plug of the three valves referred to, can assume either one of two positions, as indicated by the adjacent full line and dotted line arrows which parallel the right angles and ports in the respective normal position and particular functioning position of the valves. Only in the case of double heading, is valve DH turned to its double heading position, to directly connect the main reservoir with the large actuator cylinder.

Connected to the acknowledging valve A070 V is a pipe 26 communicating with a timing reservoir TR, and a pipe 26 provided with a constricted exhaust orifice 27, whereby pressure fluid can be entirely exhausted from the reservoir TR within a predetermined period of time, in this case approximately 15 seconds. A like 15 second exhaust orifice 27 is provided in the housing of valve Res V.

Adjacent the armature 12 of relay MR, is an acknowledging sylphon, A070 S arranged, when supplied with pressure fluid, to move the armature to attracted position and retain it in such position so long as pressure is maintained in the sylphon.

A pipe 28 leads from the main reservoir of a usual railway air brake system, to conduct pressure fluid through a strainer 29, to branched pipes 30 and 31 leading, respective lv, to the double heading valve, DH. and the reset valve Res V. The double heading valve is in turn connected by a pipe 32 to the secondary valve SV, while the acknowledging and reset valves are interconnectec by a pipe 33, having a branch pipe 20 leading therefrom to the secondary valve, SV.

The above mentioned pipe 17 is connected, by branch pipes 34 and 35, to the reset valve and the pipe 32 respectively,'there being inserted in pipe 85, a restricted aperture device 36, to materially restrict flow of pressure fluid there through.

Connected to be controlled by the double heading valve DH is a pipe 37 leading to the large actuator cylinder of usual engineers brake valve operator, such as the cylinder 11 o'fPatent1,628,454to (1S. Bushnell, the present applicant, whereby to cause a brake application upon the venting of such cylinder.

A consideration of the apparatus above described shows that, with the various parts in their normal positions and conditions, as illustrated, that is, in the positions and conditions existing under clear trafiic conditions, relay MB is energized to thus hold closed the primary valve PV. In these circumstances, the reset sylphon Res S is supplied with pressure from the main reservoir passing through valve Res V, valve SV which has its valve stem 22 in its lower position, and the constricted passage device 36. Any pressure which might have been in the timing reservoir TR has exhausted out of the vent 27 so that the acknowledging sylphon A070 S, is contracted. The double heading valve connects the large actuator cylinder to main reservoir pressure through a path including the secondary valve SV, valve Res V and strainer 29.

Assuming, for the purpose of explanation, that the car 5 passes a signal. at clear, the

trackway inductor l is in inactive condition, so that no inductive influence is felt by the receiver ll, and the various parts remain in the positions and conditions illustrated and described, with no brake application occurring.

Assume now that the car passes an inductor in active condition, that is, passes a signal at stop or caution, and no acknowledging act is performed. Unoer these conditions relay Mil. becomes {lo-energized, resulting in the release of armature 12 tier-coil, with a resulting opening of valve plug 1% ot the primary valve, valve 14 being constantly urged to open position by main reservoir pressure thereunder through pipe 1?. This vents the large actuator cylinoer through valve DH ant. the flow restricting member 36, to atmosphere through port 16 of the primary valve, and what is more important vents the sylphon Res S to atmosphere through the same port 16. On contraction of sylphon Res S valve plugs 23 and 9A- assume their upper positions, resulting in directly venting the large actuator cylinder to atmospl ere throuo'h port 18 of the secondary valve SV through a path including valve Dll, pipe 32 and valve member 23 and simultaneously cutting off the feed of main reservoir pressure to the actuator cylinder through a pate including 28, 29, 81, valve lies V, 33, 20, valve member El, 19, 32, valve DH and 37, these two functions being respectively performed by valve members 28 and 24-, and an automatic brake application results.

lad the engineman been alert, however, on passing the active inductor, the brake application could have been torstalled by operating,- the acknowledging valve A070 V, shortly before passing the inductor. On operating the valve holding it there for two or three seconds, timing reservoir is charged with pressure from the main reservoir through a path including; 28, 29, 31, llcs V in normal position, 33, Ads V in acknowledging position and 26 The acknowledging valve can then be re turned to its normal position, whereupon pressure from reservoir TR expands acknowled 'ing sylphon A076 S and maintains armature 12 of relay MR in attracted position for a period of approximately 15 seconds, regardless ot dc-cnergization of the relay. Thus the opening of the primary valve is prevented, and. no brake application is incurred.

It should be noted that the energizing circuit or the main relay, is a tuned circuit which becomes detuned upon release of the armature 12 since this, as is well recognized, changes the tuning by decreasing the inductive reactance of the circuit, whereby the normal induced voltage in the secondary windings S of the receiver is insuilicient to send enough current through such detuned secondary circuit, to pick up the main relay,

A070 V to acknowledging position and whereby, if the relay armature be retracted, it so remains until resoored by some outside agency.

With the parts in the condition existing after an automatic brake application had been incurred, in order to relieve the train from the brakes it is necessary to operate the reset means. This is accomplished by first per-- forming the acknowledging act described above whereby to restore the armature 12 of the main relay, and thus close the primary valve PV. The acknowledging valve A070 V is then turned once more to acknowledging; position to charge timing reservoir TR, and left in such position after which reset valve Res V which, to protect against misuse, is positioned to be accessible only when the car is at standstill, is turned, approximately (30, to reset position to permit pressure from the timing reservoir TR to pass through the acknowledging and reset valves and into sylphon Res S, to expand the same and move valve iuentibers and 24 of secondary valve SV, to tiepositions shown in the drawing.

At the same time, reservoir TB is connected to atmosphere through reset valve port 27 which is so chosen as to exhaust the reservoir in approximately 15 seconds. The acknowledging and reset valves are then retur; to their normal positions, which puts main reservoir pressure on Res S and the e actuator cylinder, whereupon all of the part-s are placed, remain, in the positions and conditions shown in the drawing, until another active inductor is encountered. Vent 2Y necessitates return of valve lies V to normal, within a limited period of time, to pre vent opening of valve inen'ihers 23 and 24 due to lack oi"? pressure in sylphon S.

The constricted opening; 21, in pipe 20, opcrates to prevent pressure being built up in laithe large actuator cylinde whil such eylinder is being vented through port 18, were valve member 24c to be lost, or fail to function. properly and not close. That is, pressure can. escape from the large actuator cylinder through port 18, much ts than it can be supplied to such cylinder from the main reservoir through the constricted opening 21.

The above rather specific description of one form of the invention, is given solely by way of example, and is not intended, in any manner whatsoever, in a limiting" sense. Gbviously, the invention can assume many dillerent physical forms, and susceptible oi numerous modifications, all such. forms and iodilications are intendor to be included in this application, come within the scope of the appended claims.

'laving described my invention, I now claim 1. In a train control system, a brake actuator normally under pressure and initiated when vented, a primary valve normally controlled in accordance with trailic conditions ahead and movable'to normal and reverse positions, a secondary valve moved from normal to reverse upon operation of the primary valve to reverse, a source of fluid pressure connected to the actuator through the secondary valve when normal and disconnected therefrom when reverse, means for venting the actuator upon movement to reverse of the secondary valve, a timing pressure reservoir manually chargeable, acknowledging means operable by pressure from the timing reservoir to prevent traffic control of the primary valve and maintain it normal, and manual reset means for moving the secondary valve to normal by pressure from the timing resen voir.

2. In a train control system, a brake actuator normally under pressure and initiated whenvented, a primary valve normally controlled in accordance with trafiic conditions ahead to assume normal and reverse positions, a secondary valve moved from normal to reverse upon operation of the primary valve to reverse, a source of fluid pressure connected to the actuator through the secondary valve when normal and disconnected therefrom when reverse, means for venting the actuator upon movement to reverse of the secondary valve, a timing pressure reservoir manually chargeable, acknowledging means operable by pressure from the timing reservoir to prevent traffic control of the primary valve and maintain it in normal position, and reset means for moving to normal the secondary valve by pressure from the timing reservoir only when the primary valve is in normal position.

8. In a train control system, a brake actuator normally under pressure and initiated when vented, a source of pressure, a secondary valve operable to simultaneously vent the actuator and cut it off from the source of pressure, and vice versa, a primary valve automatically controlling operation of the secondary valve, a traffic responsive carcarried means controlling actuation of the primary valve, an acknowledging device including a timing reservoir chargeable from the pressure source and means operated by pressure from the reservoir to temporarily suspend the operative relation between the primary valve and said car-carried means, and close and hold closed, the primary valve, and manual reset means for causing pressure from the timing reservoir to operate the secondary valve to its non-venting position only if the primary valve be closed at the time.

4. In a train control system, a brake actuator normally under pressure and initiated when vented, a primary valve normally controlled in accordance with traffic conditions ahead and movable to normal and reverse positions, a secondary valve moved from normal to reverse upon operation of the primary valve to reverse, a source of fluid pressure CHARLES S. BUSHNELL, 

